JPH08159231A - Screw feeding mechanism and rectilinearly moving stand for ultra-high-vacuum having its mechanism - Google Patents

Abstract

PURPOSE: To provide a screw feeding mechanism by which discharge gas in a vacuum is reduced and rotational resistance is reduced by arranging a radial ball bearing instead of a screw thread of a nut part in the screw feeding mechanism to rectilinearly move the nut part by rotating a screw shaft. CONSTITUTION: In a screw feeding mechanism 3 composed of a screw shaft 7 and a nut part 6, a radial ball bearing 13 by which rolling resistance is reduced and discharge gas is reduced, is arranged between the screw shaft 7 and the nut part 6. An angle part formed by an inside surface 23 of an inner wheel ring 22 of the radial ball bearing 13 and end surfaces 24 and 24' and a screw groove of the screw shaft 7, are brought into rolling contact with each other, and are meshed with each other, and an outer ring 20 of the radial ball bearing 13 is connected to and held by the nut part 6, and the screw shaft 7 is rotated, and the nut part 6 is rectilinearly moved. According to this, rotational resistance can be reduced even in a vacuum where a friction coefficient becomes larger than in the atmosphere, and discharge gas generated from the screw part can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a screw feeding mechanism constructed to rotate a screw shaft to linearly move a nut portion engaged with the screw shaft.
The rolling contact structure between the screw shaft and the nut portion has a good transmission efficiency, and the gas discharged from the screw feeding mechanism portion is suppressed to a small amount, which is improved to be suitable for use in an ultra-high vacuum chamber. The present invention relates to a screw feed mechanism and a linear movement base for ultra-high vacuum equipped with the screw feed mechanism.

[0002]

2. Description of the Related Art In a rectilinear moving platform for reciprocating a moving part on a rectilinear guide, a method of converting rotational motion by a motor or the like into a linear motion by a screw feeding mechanism is widely used as a means for driving the moving part. Has been done. In that case, the screw used for the screw feed mechanism is JIS-B-0.
A metric thread or JI with a triangular thread cross section such as 205
S-B-0216 metric trapezoidal screw or JIS-B-1 which is efficient for conversion from rotary motion to linear motion.
A ball screw of 191 or JIS-B-1192 is often used.

However, in a screw feed mechanism using a triangular screw or a trapezoidal screw, the screw portion and the nut portion are in sliding contact with each other. It is essential to apply a lubricant to the parts to prevent the galling phenomenon and reduce the rotational resistance. However, gas is released from the lubricant, and the released gas has a bad effect such as lowering the degree of vacuum. Therefore, it is difficult to use this type of screw feed mechanism in an ultrahigh vacuum container.

Further, in a screw feed mechanism using a ball screw, about 100 balls (steel balls) incorporated inside are normally circulated while lubricating with grease in order to make endless rolling motion. I need to do it,
Due to the gas released from the grease, it is difficult to use in the ultra-high vacuum container. Even if this ball screw is used without lubrication, it is difficult to evacuate the space in which a large number of balls circulate, and it is also difficult to use it in an ultrahigh vacuum container.

[0005]

In the above-mentioned conventional screw feed mechanism, the frictional resistance between the screw portion and the nut portion is reduced even in a vacuum where the friction coefficient is larger than in the atmosphere, and No sufficient consideration has been given to the fact that the two requirements for reducing the amount of gas released from the gas are satisfied at the same time, and the frictional resistance can be reduced sufficiently because the emphasis is placed on reducing the amount of gas released. As a result, there is a problem that a galling phenomenon occurs, and conversely, the reduction of frictional resistance is focused so much that the generation of released gas cannot be sufficiently suppressed, resulting in an increase in pressure in the vacuum container. It was Therefore, it has been difficult to realize a straight-moving base that can sufficiently withstand use in an ultra-high vacuum container by using such a straight-moving screw feed mechanism according to the related art.

Therefore, an object of the present invention is to provide a screw feed mechanism which emits less gas in a vacuum and has a small friction resistance, and further, in an ultrahigh vacuum container equipped with the mechanism. The purpose is to provide a linear moving platform suitable for use.

[0007]

In order to achieve the above object, in the present invention, the nut portion, which comprises a screw shaft and a nut portion meshed with the screw shaft, is rotated to move the nut portion straightly. In the screw feed mechanism, a radial ball bearing having a small rolling resistance and a small amount of released gas is arranged in place of the thread of the nut portion, and one of the inner ring and the outer ring of the radial ball bearing is rolled in the thread groove of the screw shaft. Contact and engage,
The other is connected and held to the nut portion.

When the inner ring side of the radial ball bearing is engaged with the thread groove of the screw shaft, the radial ball bearing is designed so that the screw shaft passes inside the inner ring of the radial ball bearing. On the contrary, when the outer ring side of the radial ball bearing is engaged with the thread groove of the screw shaft, the radial ball bearing is arranged so that the screw shaft passes through the outside of the outer ring of the radial ball bearing. It is good to be arranged.

Further, when the inner ring side of the radial ball bearing is engaged with the thread groove of the screw shaft, the radial ball bearing is such that the inner ring of the radial ball bearing is the inner surface of the inner ring and both ends of the inner ring. It can be arranged so as to engage with the thread groove of the above-mentioned screw shaft at both or either one of the two circumferential corner portions formed by the surface. For that purpose, it is preferable that the rotational center axis of the radial ball bearing is inclined with respect to the central axis of the screw shaft.

Further, when the inner ring of the radial ball bearing is engaged with the thread groove of the screw shaft at both of the circumferential corners described above, the respective engagement positions are set to the rotational direction angle of the radial ball bearing. It is desirable to set the positions at 180 degrees apart from each other. The outer ring of the radial ball bearing is perpendicular to a plane in which the outer ring includes the center axis of the screw shaft and the rotation center axis of the radial ball bearing, and the center axis of the screw shaft and the rotation center of the radial ball bearing. It is desirable that an axis passing through the intersection with the axis can be rotated with respect to the nut as an axis of rotation so that the nut is connected and held. Further, a preload is applied to the outer ring of the radial ball bearing in a direction in which the outer ring is rotatable with respect to the nut portion, in a direction in which the both corners of the inner ring of the radial ball bearing are pressed against the thread groove of the screw shaft. It is desirable to add a means for giving. Further, the outer ring of the radial ball bearing can be connected and held to the nut portion through a pin provided on the rotation axis of the outer ring with respect to the nut portion, and through two molded leaf springs. It can also be connected and held.

When the inner ring of the radial ball bearing is engaged with the thread groove of the screw shaft only at one of the circumferential corners, the outer ring of the radial ball bearing is the outer ring of the screw. The nut portion with the axis that is perpendicular to the plane including the center axis of the shaft and the rotation center axis of the radial ball bearing and does not pass through the intersection of the center axis of the screw shaft and the rotation center axis of the radial ball bearing as the rotation axis. It is desirable to be able to rotate with respect to and to be connected and held by the nut portion. Also in this case, a direction in which one of the corners of the inner ring of the radial ball bearing is pressed against the thread groove of the screw shaft in the rotatable direction of the outer ring of the radial ball bearing with respect to the nut part of the outer ring. It is desirable to add a means for applying the pre-load. Also in this case, the outer ring of the radial ball bearing can be connected and held to the nut portion via a pin provided on the rotation axis of the outer ring with respect to the nut portion, and the outer ring can be molded. It can also be connected and held via two leaf springs.

Further, by using the screw feeding mechanism having the above-mentioned structure as a means for driving the moving part which reciprocates on the straight guide, the straight moving table suitable for use in the ultra-high vacuum container is obtained. To be

[0013]

In the screw feed mechanism including the screw shaft and the nut portion, a radial ball bearing having a small rotational resistance and a small amount of released gas is provided between the screw shaft and the nut portion instead of the thread of the nut portion. The inner ring side (or outer ring side) of the radial ball bearing is brought into rolling contact with the thread groove of the screw shaft so as to engage with each other, and the outer ring side (or inner ring side) is connected and held by the nut portion, thereby screw feeding. It is possible to realize a straight advance screw feed mechanism which has a high transmission efficiency and which emits less gas in a vacuum.

More specifically, in a state where the screw shaft is passed through the inside of the radial ball bearing, the inner ring of the radial ball bearing has two circumferential corners formed by the inner surface of the inner ring and both end surfaces of the inner ring. When the screw shaft is rotated by arranging the rotation axis of the radial ball bearing with respect to the central axis of the screw shaft so as to mesh with the screw groove of the screw shaft in both (or one) of , The inner ring of the radial ball bearing rotates in rolling contact with the thread groove of the screw shaft at both (or one) of the circumferential corners, and the nut portion connected to the outer ring side of the radial ball bearing is rotated. Move straight. At this time, even if the frictional force between the inner ring of the radial ball bearing and the screw shaft is small and a slip in the rotational direction occurs between the two, the radial ball bearing slides in the axial direction of the screw shaft. However, the nut portion moves linearly exactly by one lead of the screw shaft during one rotation of the screw shaft.

In the screw feed mechanism of the present invention, the meshing state of the screw shaft and the radial ball bearing connected and held by the nut portion is determined by the pitch of the screw shaft, the outer diameter, the angle of the thread groove, and , The inner diameter of the radial ball bearing, the inner ring width, and the shape of the corners of the circumferential corner formed by the inner ring inner surface and the inner ring end surface, etc., but some of these parameters may change slightly. It is possible to accurately mesh the screw shaft and the radial ball bearing without backlash.

As described above, in the present invention, the radial ball bearing arranged between the screw shaft and the nut portion instead of the thread of the nut portion to be engaged with the screw shaft makes rolling contact with the thread groove of the screw shaft. As a result, the rotation of the screw shaft is converted into the linear movement of the nut portion, so that the rolling resistance between the two is small and the transmission efficiency when converting the rotational movement into the linear movement is high. Also, in a radial ball bearing, contact between balls does not occur unlike ball screws, so it is possible to use it without lubrication, and it is also easy to use a solid lubricant that does not adversely affect the vacuum. Is. Further, in a radial ball bearing, since there is little internal space where it is difficult to evacuate like a ball screw, the degree of vacuum in the use space is not adversely affected.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1, FIG. 2 and FIG. 3 show a schematic structure of an ultra-high vacuum linear movement base according to an embodiment of the present invention. 1 is a top view, FIG. 2 is a front side view, and FIG. 3 is a right side view. In the figure, a rectilinear moving base 1 is configured such that a moving part 1 ″ reciprocates linearly on a rectilinear guide 2 provided on a fixed part 1 ′. The screw feeding mechanism 3 according to the present invention provided on the front side surface converts the rotational movement from the outside into a rectilinear movement. Stoppers 4 for restricting the movement range of the moving portion 1 ″ are provided at both ends of the fixed portion 1 ′ in the longitudinal direction.

FIG. 4 is a sectional view showing a portion of the screw feeding mechanism 3 in FIG. The screw feeding mechanism 3 is roughly classified into a screw shaft portion 5 side attached to the fixed portion 1 ′ side of the moving table 1 and a nut portion 6 side attached to the moving portion 1 ″ side of the moving table 1.

On the side of the screw shaft portion 5, there is rattling of the screw shaft 7, a bearing 8 for supporting the screw shaft 7, a housing 9 for accommodating the bearing 8 and mounting the bearing 8 on the fixed portion 1'of the moving base 1, and a bearing 8. A preload spring 10 for applying a constant axial preload to the bearing 8 in order to hold the lost screw shaft 7 with high accuracy, and a ring for preventing the preload spring 10 and the end surface of the screw shaft 7 from directly contacting the bearing 8. 11
11 ', and a coupling 12 for clamping the screw shaft 7 while receiving a rotational movement from the outside and compressing the preload spring 10 to a predetermined length.

FIG. 5 shows a detailed structure of the nut portion 6 side.
On the nut portion 6 side, a radial ball bearing 13 that meshes with the thread groove of the screw shaft 7 instead of the screw thread of the nut, a housing 14 that houses the radial ball bearing 13, and a holding ring 15 that fixes the outer ring of the radial ball bearing 13 to the housing 14. , Housing 14 screw shaft 7
A pin 16 that holds the pin 16 so that it can rotate about an axis that passes through and is perpendicular to the central axis of the radial shaft bearing 13 and a linear movement B of the radial ball bearing 13 that accompanies the rotational movement A of the screw shaft 7; A block 17 that transmits to the moving portion 1 ″ side of the moving table 1, a preload spring 18 that is housed in the block 17 and that applies a preload to the housing 14 in a rotation direction (C direction) about the pin 16 as an axis, a preload spring 18
The push rod 19 transmits the repulsive force to the radial ball bearing 13 via the housing 14. The central axis of the pin 16 in this embodiment is
In FIGS. 1 and 4 to 6, it is set so as to pass through the central axis of the screw shaft 7 and be perpendicular to both the central axis and the paper surface.

FIG. 6 shows in detail the meshing state of the screw shaft 7 and the radial ball bearing 13. The radial ball bearing 13 includes an outer ring 20, a ball 21, and an inner ring 22.
The screw shaft 7 is arranged so as to pass inside the inner ring 22 of the radial ball bearing 13. The screw shaft 7 and the radial ball bearing 13 are meshed with each other by the one corner formed by the inner surface 23 of the inner ring 22 and one end surface 24 of the inner ring 22 and the other by the inner surface 23 of the inner ring 22 and the other end surface 24 ′ of the inner ring 22. Of the radial ball bearing 13 with respect to each other by 180 degrees with respect to each other.
It is carried out by rolling contact with the side surfaces of the screw groove of the screw shaft 7 at positions that are offset from each other. In this embodiment, since both corners of the inner ring 22 are in contact with the thread groove side surfaces of the screw shaft 7, the inner surface portion 23 of the inner ring 22 is not in contact with the thread groove, but as shown in FIG. Then, the pin 16 holding the radial ball bearing 13 is moved in parallel on the paper surface and moved to another place, and only one corner of the inner ring 22 is engaged with the screw groove of the screw shaft 7, and this one place It is also possible to configure that the inner surface portion 23 and the end surface portion 24 (or the end surface portion 24 ') of the inner ring are in rolling contact with the thread groove at the meshing portion. Further, in this embodiment, the screw shaft 7 is arranged so as to pass through the inner ring 22 of the radial ball bearing 13, but as shown in FIG.
It is also possible to dispose one or a plurality of radial ball bearings 13 around the screw shaft 7 and to engage the outer ring side of these radial ball bearings 13 with the thread groove of the screw shaft 7. In this case, it goes without saying that the inner ring side of the radial ball bearing 13 is connected and held to the nut portion 6.

Next, the operation of each part of the apparatus during the reciprocating rectilinear movement of the moving table moving section 1 "having the above-mentioned apparatus configuration will be described with reference to FIGS. 4 to 6. As shown in FIG.
The screw shaft 7 is held by a housing 9 fixed to the fixed portion 1 ′ of the movable table 1 via two bearings 8, and the screw shaft 7 is preloaded to the right in the axial direction by the repulsive force of the preload spring 10. Pressure is applied. Therefore, the screw shaft 7 is accurately held so as not to rattle the housing 9 in the axial direction and the radial direction. In this state, first, the rotational movement from the external drive device is transmitted to the screw shaft 7 via the coupling 12. In the following, a case will be described in which the thread winding direction of the screw shaft 7 is the right-hand screw direction and the rotation direction of the screw shaft 7 is the A direction shown in the drawing.

By the rotation of the screw shaft 7 in the A direction, the radial ball bearing 1 meshed with the screw groove thereof.
3 is pushed and moved in the direction B shown. At this time, the portion pushed by the screw shaft 7 is the radial ball bearing 1
3 is a corner portion of the inner ring 22 on the side of the end face 24 ', but this portion is in rolling contact with the thread groove of the screw shaft 7, and the inner ring 22 can rotate inside the outer ring 20 when the screw shaft 7 rotates. The occurrence of sliding friction at this contact portion is extremely small.
Therefore, the nut portion 6 can be efficiently moved straight by the rotation of the screw shaft 7, and the moving portion 1 ″ of the moving table 1 attached to the nut portion 6 can be moved accurately with a small rotational force.

The radial ball bearing 13 is shown in FIG.
As shown in FIG. 7, a preload is applied by the preload spring 18 via the housing 14 and the push rod 19 in the C direction (the direction in which the corner portion of the inner ring 22 is meshed with the thread groove of the screw shaft 7). When the screw shaft 7 is rotated, the nut 6 and the moving base moving unit 1 ″ move due to the reaction force of this preload, but when the moving unit 1 ″ reaches the stroke end and is pressed against the stopper 4, the screw shaft 7 rotates. By doing so, the thrust generated by the lead overcomes the preload by the preload spring 18 described above, so that the radial ball bearing 13 in the housing 14 is acted on by a rotational force in the direction opposite to the C direction in the drawing, The shaft 7 and the inner ring 22 are disengaged from each other.
For this reason, even if the moving shaft 1 ″ reaches the stroke end, even if the screw shaft 7 is still rotated, the respective parts of the device are not damaged.

FIG. 9 shows another embodiment in which the method of supporting the radial ball bearing 13 is changed. In this embodiment,
The housing 14, the pressing ring 15, and the pin 1 shown in FIG.
6, instead of the preload spring 18 and the push rod 19, 2
A plurality of molded leaf springs 25 are provided, the radial ball bearing 13 is supported by the leaf springs 25, and an axis line that is substantially perpendicular to both the rotation center axis of the radial ball bearing 13 and the center axis line of the screw shaft 7. The radial ball bearing 13 is pressed down in the direction of rotation about the center (direction C). With this supporting method, the device structure can be further simplified as compared with the supporting method shown in FIG. 5, and the manufacturing cost can be reduced.

In the above-mentioned embodiments, the commercially available standard products are used as they are for the radial ball bearing 13 and the screw shaft 7, but the screw feed mechanism can be obtained at a low cost and with relatively high precision. However, in order to further improve the feeding accuracy, as shown in FIG. 10, the shape of the thread groove of the screw shaft 7 and the shape of the corner formed by the inner surface 23 of the inner ring 22 of the radial ball bearing 13 and both end surfaces 24, 24 '. It is also effective to change the shape to be more suitable for meshing.

Further, in the above embodiment, except for the example of FIG. 8, the number of radial ball bearings used is one per screw shaft, but by using a plurality of radial ball bearings, the movement of the nut part can be prevented. It is possible to increase thrust.

According to the above embodiment, in the screw feed mechanism including the screw shaft and the nut portion, a radial ball bearing is arranged in place of the screw thread of the nut portion, and this is brought into rolling contact with the thread groove of the screw shaft. By doing so, the rotational movement of the screw shaft is converted into the linear movement of the nut portion, so the contact resistance between the screw shaft and the nut portion is small, the conversion efficiency is high, and it is also necessary to use a lubricant. Since there is no such gas, a screw feed mechanism that emits less gas can be realized. The result is a screw feed mechanism that is very convenient for use in ultra high vacuum.

In addition, even a very small object with an inner diameter of 1 mm, which is commercially available as a standard product, and a miniature screw of JIS-B-0201, which is applied with a minimum outer diameter of 0.3 mm and a pitch of 0.08 mm, etc. Is also used in combination as in the above-described embodiment, an effect that a very small screw feed mechanism with a small lead can be obtained.

[0031]

According to the present invention, the radial ball bearing arranged in place of the screw thread of the nut portion is brought into rolling contact with the thread groove of the screw shaft to convert the rotation of the screw shaft into the linear movement of the nut portion. Therefore, the contact resistance between the screw shaft and the nut portion is reduced, and the conversion efficiency from the rotational movement to the linear movement can be increased. Also, radial ball bearings can be used without lubrication because contact between balls does not occur unlike ball screws, but in some cases solid lubrication does not adversely affect vacuum. Agents can also be used. Further, since the radial ball bearing has a small internal space, such as a ball screw, which is difficult to evacuate, it is less likely to adversely affect the degree of vacuum in the room in which it is used.

From the above, the two requirements of simultaneously reducing the rotational resistance of the screw shaft and simultaneously reducing the gas released from the screw shaft in a vacuum where the friction coefficient is larger than in the atmosphere are satisfied. Therefore, it is possible to provide a linear screw feed mechanism suitable for use in an ultra-high vacuum chamber that does not cause a galling phenomenon or increase the pressure in the vacuum container due to the released gas.

[Brief description of drawings]

FIG. 1 is a top view showing a schematic configuration of an ultra-high vacuum linear movement base according to an embodiment of the present invention.

FIG. 2 is a front side view of the ultra-high vacuum linear movement base shown in FIG.

FIG. 3 is a right side view of the ultra-high vacuum linear movement base shown in FIG.

FIG. 4 is a partial cross-sectional view showing a detailed structure of a screw feeding mechanism 3 portion in FIG.

5 is a partial cross-sectional view showing the detailed structure of the nut portion 6 side in FIG.

6 is a partial cross-sectional view showing details of a meshed state of the screw shaft 7 and the radial ball bearing 13 in FIG.

FIG. 7 is a partial cross-sectional view showing another example of the engagement state of the screw shaft 7 and the radial ball bearing 13 in the screw feeding mechanism of the present invention.

FIG. 8 is a partial cross-sectional view showing still another example of a meshed state of the screw shaft 7 and the radial ball bearing 13 in the screw feed mechanism of the present invention.

FIG. 9 is a partial cross-sectional view showing another example of a method of holding the radial ball bearing 13 in the screw feeding mechanism of the present invention.

FIG. 10 is a cross-sectional view showing another modified example of the meshing portion shape (screw groove shape and inner ring corner portion shape) of the screw shaft 7 and the radial ball bearing 13 in the screw feeding mechanism of the present invention.

[Explanation of symbols]

1 ... movable table, 1 '... fixed part,
1 ”... moving part, 2 ... straight guide,
3 ... Screw feed mechanism, 4 ... Stopper, 5
… Screw shaft, 6… Nut, 7…
Screw shaft, 8 ... Bearing, 9 ...
Housing, 10 ... Preload spring, 11 ...
Ring, 11 '... Ring, 12 ...
Coupling, 13 ... Radial ball bearing, 14 ... Housing, 15 ...
Ring, 16 ... Pin, 17 ... Block, 18 ... Preload spring, 19 ... Push rod, 20 ... Outer ring, 2
1 ... Ball, 22 ... Inner ring, 23
... Inner surface of inner ring, 24 ... One end surface of inner ring, 2
4 '... other end surface of inner ring, 25 ... leaf spring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masafumi Kinyu, 1-280 Higashi Koikeku, Kokubunji City, Tokyo Metropolitan Research Laboratory, Hitachi, Ltd. (72) Toshiyuki Matsubara 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. Central Research Laboratory

Claims (14)

[Claims] 1. A screw feed mechanism, comprising a screw shaft and a nut portion meshing with the screw shaft, for linearly moving the nut portion by rotating the screw shaft, wherein a radial ball bearing is used instead of the thread of the nut portion. A screw feed mechanism in which one of an inner ring and an outer ring of the radial ball bearing is engaged with a thread groove of the screw shaft and the other is connected and held by the nut portion. 2. The screw feed mechanism according to claim 1, wherein the radial ball bearing is arranged so that the screw shaft passes through an inner side of an inner ring of the radial ball bearing. 3. The screw feed mechanism according to claim 1, wherein the radial ball bearing is arranged so that the screw shaft passes through an outer side of an outer ring of the radial ball bearing. 4. The inner ring of the radial ball bearing comprises:
The corners formed by the inner surface of the inner ring and one end surface of the inner ring and the corners formed by the inner surface of the inner ring and the other end surface of the inner ring are engaged with the thread groove of the screw shaft. The screw feed mechanism according to claim 2, wherein 5. The inner ring of the radial ball bearing comprises:
Only at one corner of the corner formed by the inner surface of the inner ring and one end surface of the inner ring and the corner formed by the inner surface of the inner ring and the other end surface of the inner ring, the screw shaft The screw feed mechanism according to claim 2, wherein the screw feed mechanism is engaged with the screw groove. 6. The inner race of the radial ball bearing engages with the thread groove of the screw shaft at each of the two corners at two positions which are 180 degrees apart from each other in the rotational direction angle of the radial ball bearing. The screw feed mechanism according to claim 4, wherein the rotation center axis of the radial ball bearing is arranged to be inclined with respect to the center axis of the screw shaft. 7. The rotation center axis of the radial ball bearing is tilted with respect to the center axis of the screw shaft so that the inner ring of the radial ball bearing meshes with the thread groove of the screw shaft only at one of the corners. 6. The screw feed mechanism according to claim 5, wherein the screw feed mechanism is arranged as follows. 8. The outer ring of the radial ball bearing comprises:
The outer ring is perpendicular to a plane including the central axis of the screw shaft and the central axis of rotation of the radial ball bearing with respect to the nut portion, and the intersection of the central axis of the screw shaft and the central axis of rotation of the radial ball bearing. The screw feed mechanism according to claim 4 or 6, wherein the screw feed mechanism is connected and held to the nut portion so as to be rotatable about a line passing through the rotation axis line. 9. The outer ring of the radial ball bearing comprises:
The outer ring is perpendicular to a plane including the central axis of the screw shaft and the central axis of rotation of the radial ball bearing with respect to the nut portion, and the intersection of the central axis of the screw shaft and the central axis of rotation of the radial ball bearing. The screw feed mechanism according to claim 5 or 7, wherein the screw feed mechanism is rotatably connected to the nut portion so that a wire that does not pass through can be rotated as a rotation axis. 10. A direction in which the both corners of the inner ring of the radial ball bearing are pressed against the thread groove of the screw shaft in the rotatable direction with respect to the outer ring of the radial ball bearing with respect to the nut part of the outer ring. 9. The screw feed mechanism according to claim 8, further comprising a means for applying the preload. 11. A direction in which one of the corner portions of the inner ring of the radial ball bearing is pressed against a thread groove of the screw shaft in a direction in which the outer ring of the radial ball bearing can rotate with respect to the nut portion of the outer ring. 10. The screw feed mechanism according to claim 9, further comprising means for applying the preload. 12. The outer ring of the radial ball bearing is connected and held to the nut portion via a pin provided on a rotation axis of the outer ring with respect to the nut portion. 9. The screw feed mechanism according to item 9. 13. The outer ring of the radial ball bearing is connected and held to the nut portion via two molded leaf springs.
The screw feed mechanism described in. 14. A rectilinear moving base having a rectilinear guide and a moving part reciprocating on the rectilinear guide, which is used in an ultrahigh vacuum container, and is a drive for reciprocating the moving part. A linear movement base for ultra-high vacuum, characterized by using the screw feed mechanism according to any one of claims 1 to 12 as means.